The present invention relates to prosthetic heart valves generally, and more particularly to heart valves employing preserved animal tissue or flexible polymers as leaflets.
Prosthetic heart valves have been used for more than 30 years for replacement of diseased natural heart valves. The use of preserved porcine heart valves alone, or in association with a reinforcing stent or frame has been widely practiced. Valves constructed using preserved pericardial or dura mater tissue, mounted to stents or frames have also been employed. It has also been repeatedly proposed to employ flexible synthetic materials as substitutes for preserved tissue in valves of this type.
One proposal for constructing a synthetic heart valve employing flexible polymer valve leaflets is set forth in U.S. Pat. No. 4,339,831 issued to Johnson. The disclosed valve employs a framework of three curved flexible struts each joined at one end to a common central point and extending therefrom in the same direction, at equal angles from each other with the free ends of the struts located spaced equidistantly from one another. The free ends are each provided with sewing pads for attachment of each free end separately to the natural tissue annulus by means of sutures. The valve is provided with a hemispherically shaped membrane adapted to fit over and be attached to the framework so that three partial hemispheric segments or leaflets are defined. Each leaflet extends between adjacent frame struts in such a manner that the free edge of each leaflet can contact the tissue annulus when the valve is closed and can move inward, away from the tissue annulus when the valve is open.